Windows: Reload config on manual DNS changes

[bradh352]

The NotifyIpInterfaceChange() method only notifies of automatic changes, such as via DHCP or interfaces going up or down. However, someone editing the DNS settings manually would not trigger a notification.

Use RegNotifyChangeKeyValue() to monitor HKLM\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\Interfaces and HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces to pick up these changes.

This new check also works when using the OpenWatcom compiler as the symbols are available, so they have been enabled (though NotifyIpInterfaceChange() method is disabled for OpenWatcom still due to the linker libraries missing this symbol).

NOTE: it does appear that about 5 events get triggered for some reason, it doesn't seem to hurt anything, but it will actually cause it to re-read the configuration multiple times.

Fixes Issue: #761
Fix By: Brad House (@bradh352)

[dg0yt]

These changes seem to have broken UWP builds. Is this intentional?
Observed in vcpkg (microsoft/vcpkg#40213) and triggering downstream changes there. (I think I also saw existin packages avoiding c-ares for UWP.)

[bradh352]

definitely not intentional. We had added an AppVeyor CI build for that, but then there was some later breakage due to an MSVC bug ( https://developercommunity.visualstudio.com/t/clexe-compiler-error-C1007-when-compili/10486219 ) so we had to disable it until AppVeyor upgraded the MSVC version, so UWP hasn't been tested in a while.

I'll see if we can switch to GitHub Actions for the UWP build to see if we can fix things there.

[bradh352]

fixed in 3fd5925